An Empirical Transmitted EPID Dosimetry Method using a Back-Projection Algorithm
Background: The present study aimed to introduce a rapid transmission dosimetry through an electronic portal-imaging device (EPID) to achieve two-dimensional (2D) dose distribution for homogenous environments. <br />Material and Methods: In this Phantom study, first, the EPID calibration curve...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Shiraz University of Medical Sciences
2019-10-01
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| Series: | Journal of Biomedical Physics and Engineering |
| Subjects: | |
| Online Access: | http://jbpe.sums.ac.ir/article_45725_be0e729814850502df63019abdc83b3a.pdf |
| Summary: | Background: The present study aimed to introduce a rapid transmission dosimetry through an electronic portal-imaging device (EPID) to achieve two-dimensional (2D) dose distribution for homogenous environments. <br />Material and Methods: In this Phantom study, first, the EPID calibration curve and correction coefficients for field size were obtained from EPID and ionization chamber. Second, the EPID off-axis pixel response was measured, and the grey-scale image of the EPID was converted into portal dose image using the calibration curve. Next, the scattering contribution was calculated to obtain the primary dose. Then, by means of a verified back-projection algorithm and the Scatter-to-Primary dose ratio, a 2D dose distribution at the mid-plane was obtained. <br />Results: The results obtained from comparing the transmitted EPID dosimetry to the calculated dose, using commercial treatment planning system with gamma function while there is 3% dose difference and 3mm distance to agreement criteria, were in a good agreement. In addition, the pass rates of γ < 1 was 94.89% for the homogeneous volumes. <br />Conclusion: Based on the results, the method proposed can be used in EPID dosimetry. |
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| ISSN: | 2251-7200 2251-7200 |